Control system

ABSTRACT

A control system, suitable for use as a two-hand safety control system, for producing an output signal to operate a device comprising a first fluid pulse generator generating a first fluid pulse in response to a manual force (e.g., depressing a first push-button), a second fluid pulse generator generating a second fluid pulse in response to another manual force (e.g., depressing a second push-button), and a fluid-responsive switch responsive only to substantially simultaneous receipt of these pulses to produce the output signal.

United States Patent [191 Trussell et al. p

[11] 3,811,284 May 21, 1974 l CONTROL SYSTEM [75] Inventors: Donald H.Trussell, 23 Princeton Rd., Burlington, Mass. 01803; Philip A Surette,Reading, Mass.

[73] Assignee: said Trussel, by said Surette [22] Filed: July 6, 1972[21] Appl. No.: 269,416

f [52] US. Cl 60/533, 91/424, 60/407, 60/567 [51] Int. Cl. FlSb 13/04[58] Field of Search 60/54.5 R, 62.5 R, 533,

[56] References Cited 7 UNITED STATES PATENT-S 1 W971 Wright 8/l92'5Davis.....

3,553,967 l/l97l Porter et al. 60/54.5 R

Primary Exdminer-Edgar W. Geoghegan Assistant Examiner-A. M. Zupcic IAttorney, Agent, or FirmCharles Hieken; Jerry Cohen [57 ABSTRACT Acontrol system, suitable for use as a two-hand safety control system,for producing an output signal to operate a device comprising a firstfluid pulse generator generating a first fluid pulse in response to amanual force (e.g., depressing a first push-button), a second fluidpulse generator generating a second fluid pulse in response to anothermanual force (e.g., depressing a second push-button), and afluid-responsive switch responsive only to substantially simultaneousreceipt of these pulses to produce the output signal.

18 Claims, 3 Drawing Figures PATENTEDNAYRI M4 SHEET 1 OF 2 CONTROLSYSTEM FIELD .OF INVENTION ator employs both hands simultaneously, orsubstantially simultaneously in order to operate a device.

BACKGROUND OF INVENTION Recent federal safety legislation andregulations have made it a requirement that potentially dangerousinachinery, such as jigs, presses, and various other pinching-typedevices, be equipped with two hand control systems, in order to occupyboth of the operators hands while the machinery is operated. Suchcontrols must also demand substantially simultaneous or concurrentoperation, so that, for example, successively operating the two controlswith one hand is ineffective to operate the machinery. In addition, thecontrol must be readily retrofit to existing devices, and should be bothreliable and not excessively costly to purchase or install.

SUMMARY OF INVENTION It is the object of the present invention toprovide a novel, reliable and economical control system for operatingdevices.

Another object is to provide a tow hand safety control system whichrequires substantially simultaneous operation of a control with each ofan operators hands, and which can be simply retrofit to existingdevices, aswell as incorporated into new devices.

A further object is to provide a reliable and economical control systemwhich requires no pneumatic, hydraulic, or electrical power sourcesother than the manual force resulting from an operators depressing apush button.

Another object is to provide a safety control system for operatingpinching-type devices such as jigs, presses, and the like.

The invention features a control system for producing an output signalto operate a device comprising a first fluid pulse generator generatinga first fluidpulse in responseto a manual force, a second fluid pulsegenerator generating a second fluid pulse in response to another manualforce, and a fluid-responsive switch responsive only to substantiallysimultaneous receipt of these pulses to produce the output signal. Thepulse generators are preferably spaced apart so that an oper-, ator canapply only'one manual force with each hand, and each'generator comprisesa push button which is depressed to generate the pulse (by acting upon,e.g., a piston. or a flexible fluid-confining member such as adiaphragm), and. for repeated operation, is biased to return from itsdepressed position when the manual force is removed. The inventionincludesmeans for requiring an operator to substantially simultaneouslyeffect first and second force changes, such as by depressing respectivepush buttons, to actuate the fluid responsive switch to assume a firstcondition for producing the output signal and to always assume a secondcondition preventing the occurrence of the output signal shortly afterassuming the first condition, this means including the first and secondpulse generators and means for releasing pressure following a change inapplied manual force even when the manual force persists.

A preferred fluid-responsive switch comprises fluidsensitive sealingmeans (e.g., diaphragm means) having a fluid-responsive side. A pulseinlet port for first pulses and a pulse inlet port for second pulses arelocated on opposite sides of the sealing means. The switch also has afluid outlet port, and the sealing means is responsive to the increasein pressure resulting from action of a fluid pulse on one side to causean increase in pressure at the fluid outlet port, when a fluid pulse isreceived on its other side. Dissipating means (e.g., a bleed valveopening orifice, port or other suitable devices or mechanisms) may beprovided to dissipate the increased pressure at the responsive side ofthe sealing means in a selected time interval. Unless pulses arereceived at both sides of the sealing means substantiallysimultaneously, no fluid output, i.e., no increase in pressure, resultsat the fluid outlet port. A fluid responsive output device is connectedto the fluid outlet port to produce an output signal operating thedevice upon receiving a fluid output from the fluid outlet port. I

Thus,.the pulse" produced when a push-button is depressed causes ,a'pressure increase within the fluidresponsive switch. If, because ofsubstantially simultaneous depression of the pushbuttons, this increasein pressure cannot be relieved, the pressure at the fluid output portwill also increase, and the fluid-responsive output device, responsiveto this increase in pressure at the fluid output port, will produce anoutput signal operating the device.

Other objects, features and advantages will be apparent to one skilledin the art from the following descrip-' tion of a preferred embodimentof the invention, taken together with the attached drawings thereof,inwhich:

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF PREFERRED EMBODIMENTSFIG. l shows a two hand control system 10, which produces fluid pulsesoperable to interconnect a power supply PS to a device D, operated bysubstantially simultaneously depression by an operator of twospacedapart push buttons. In particular, control system 10 has a firstpneumatic pulse generator 12, a second pneumatic pulse generator 14, anda pulse-responsive switching system comprising a fluid-responsivepneumatic switch 16 and an output device 18.

Pulse generator 12 includes a housing 20 containing an externallyaccessible'push button 22 connected to a piston rod 24, which carries onits end a piston head 26, slidably movable in a cylinder 28 against abiasing compression spring 29. Similarly, pulse generator 14 includes anidentical housing 30, push button 32, piston rod 34, piston head 36,cylinder 38 and spring 40.

At the end of cylinder 28 of first pulse generator 12 is a first pulseoutlet port 42, and at the end of cylinder 38 of second pulse generator14 is a second pulse outlet port 44.

Pneumatic switch 16 has a housing 50, having a lower chamber 52 and anupper chamber 54, separated by a flexible diaphragm 56, which is securedat its periphery to housing 50. A barrier 58 is provided to define theopening 60, which is located substantially in the middle of thediaphragm 56. A first pulse inlet port 62 is connected, throughpneumatic tube 64, to first pulse outlet port 42 of pulse generator 12,and opens into lower chamber 52. A second pulse inlet port 68 isconnected, through pneumatic tube 70, to second pulse outlet port 44 ofpulse generator 14, and is in communication through passage 72 withupper chamber 54. A vent port 74 also opens into chamber 54 betweenbarrier 58 and diaphragm 56, and is, as shown, open to atmosphere. Ableed valve 76 establishes communication,

through bleed passage 78, between lower chamber 52 and, as shown,atmosphere. A fluid outlet port 80 is in communication with upperchamber 54, and, through pneumatic tube 82, with the inlet 84 of outputdevice 18.

Output device 18, as illustrated, is an electric switch which has ahousing 86 supporting a diaphragm 88, which is in turn connected throughconnector rod 90 to control member 92. Control member 92 is pivotallymounted at its end 94 on housing 86, carries a contact member 96 on itsother end, and is biased by compression spring 97 so that Contact member96 is normally separated from fixed contact member 98. For purposes ofillustration, contact member 96 is electrically connected, throughcontrol member 92, to the power source PS, and contact member 98 iselectrically connected to the device D to be operated. Thus, operatingpower is supplied to the device D only when the,

contact members 96, 98 are engaged, and no power is supplied-Le, thedevice'will not operate-when the contact members are separated, as inFIG. 1. In practice, the output device 18 can be any switching device,whether electrical, magnetic, fluid, or otherwise responsive toreception of a fluid output from pneumatic switch 16 to produceaosi'gnal operating or controlling or otherwise acting upon the deviceD, and may be independent of whether electrical, magnetic, fluid, orother power is utilized for operating the device.

The operation of the device is apparent from a comparison of FIGS. 1 and2. Depressing push button 220! first pulse generator 12 generates apneumatic pulse from cylinder 28 which by pneumatic communicationthrough tube 64 and inlet 62 into chamber 52 causes an at leastmomentary increase in pressure in chamber 52. Since chamber 52 andchamber 53 are both normally at the same (atmospheric) pressure byreason of vent port 74 and bleed valve 76 respectively, as shown in FIG.1 in their normal OFF" states, the increase in pressure in chamber 52flexes or expands diaphragm 56 so that it seals opening 60, as shown inFIG. 2. If, while the diaphragm is expanded, push button 32 of secondpulse generator 14 is depressed, a pneumatic pulse is thereby generatedfrom cylinder 38. Since opening 60 is sealed by diaphragm 56, thissecond pneumatic pulse, through tube 70, inlet 68 and passage 72increases the pressure in chamber 54 and therefore also by pneumaticcommunication through outlet port 80, tube 82, and inlet 84, increasesthe pressure upon diaphragm 88 of output device 18. This increase inpressure expands or flexes diaphragm 88, which in turn piv- 4 otscontrol member 92 against biasing spring 97 bringing contact member 96into electrical contact with fixed contact 98, to supply power to thedevice D. If bleed valve 78 is open, as shown, to a low pressure sourcesuch as atmosphere, then the output device 18 will operate as amomentary electric unit, since, as soon as the increase in pressure dueto the first pulse is dissipated from chamber 52 through valve 78,diaphragm 56 will begin to return to its unflexed position. The pressureon diaphragm 88 is then relieved through tube 82, port 80, opening 60and vent port 74, and the contacts 96, 98 are again disengaged, openingswitch 18 through tube 82, port 80, opening 60, and vent port 74 toatmosphere.

The two-hand, substantially simultaneous operation of the system willnow be apparent. If only push button 32 of pulse generator 14 isdepressed, the increase in pressure in chamber 54 will be relievedthrough opening 60, and vent outlet 74. If only push button 22 of pulsegenerator 12 is depressed, the increase in pressure in chamber 52 willmomentarily expand or flex diaphragm 56, and then be dissipated throughbleed valve 78, returning the diaphragm to its FIG. 1 position. It isonly when depressing push button 32 of pulse generator 14 produces anincrease in pressure in chamber 54 which encounters an expandeddiaphragm, and hence a sealed opening 60, that there will be an increasein pressure at outlet to be transmitted to output device 18. Although aslight delay between pushing button 32 and then button 22 may result inthe pressure in upper chamber 54 being entirely relieved through ventport 74 before the diaphragm 56 expands to seal opening 60, the timedelay due to lack of precise coordination by the operator in exactlysimultaneously depressing the buttons it not normally of such durationas to prematurely relieve the pressure in chamber 54. The ordinarilycoordinated operator can achievethe required substantial simultaneityrepeatedly without difficulty. I

FIG. 3 shows another push-button arrangement in a control systemotherwise identical in construction and operation to that of FIGS. 1 and2. The difference resides in utilizing flexible diaphragms in lieu ofthe pneumatic pistons of FIGS. 1 and 2. In particular, pulse generator 112 (shown in the undepressed or OFF position) includes a housinghavingacentral base 122, into which is press-fit an end plug 124 havinga passage 126, which is in communication with tube 64. A shaft 128 istrapped by E-ring 130 and the shoulder 132 of bore 122 within bore 122.A flexible diaphragm 134 is secured between E-rings 136 and collar 138to shaft 128. Biasing spring 140 is held within diaphragm 134 betweenhousing 120 and collar 138. The shaft 128 has an outer threaded portiononto which is threadably secured push button 142. Collar 144 and theouter skirt 146 of diaphragm 134 are secured to housing 120 by hold-downscrews 148, which extend into the housing (not shown).

Pulse generator 114 is'identically structured, like parts beingindicated by primed numbers. Pulse generator 114 is shown with pushbutton 142 depressed, which decreases the fluid (pneumatic) volumeconfined by diaphragm 134, to generate a fluid pulse in being producedwhen only one button is depressed, as shown in FIG. 3).

Other embodiments will occur to those skilled in the art and are withinthe following claims.

What is claimed is:

1. A control system for producing an output signal to operate a devicecomprising,

a first fluid pulse generator generating a first fluid pulse only inresponse to a first manual force change,

a second fluid pulse generator generating a second fluid pulse only inresponse to a second manual force change,

fluid responsive switching means for providing an output signal whenactuated to assume a first condition,

first means coupled to said first and second pulse generators forrequiring an operator to substantially simultaneously effect said firstand second force changes to produce said first and second fluid pulsessubstantially simultaneously to actuate said fluid responsive switchingmeans to assume said first condition,

and second means for causing said fluid responsive switch to alwaysassume a second condition preventing the occurrence of said outputsignal shortly after assuming said first condition.

2. A control system according to claim 1 wherein said first and secondfluid pulse generators are spaced apart in a manner allowing an operatorto apply only onesaid manual force with each hand.

3. A control system according to claim 1 wherein each said fluid pulsegenerator "comprises a control member movable over a distance togenerate said pulse. 7

4. A control system according to claim 3 wherein each said fluid pulsegenerator comprises a manually depressible pushbutton connected to saidcontrol member.

5. A control system according to claim 1 wherein at least one of saidfluid pulse generators comprises a fluid cylinder having an outlet, apiston movable in said cylinder to displace fluid through said outlet, amanually depressible push button connected to said piston, and biasingmeans biasing said piston away from said outlet in the absence of manualforce on said pushbutton.

6. A control system according to claim I wherein at least one of saidfluid pulse generators comprises a fluid chamber having a flexiblefluid-confining member and having a fluid outlet, and a manuallydepressible push button connected to said fluid-confining member, saidbutton, when depressed, decreasing the fluid volume confined by saidmember to generate a fluid pulse at said outlet.

7. A control system according to claim wherein said flexiblefluid-confining member is a flexible diaphragm.

8. A control system according to claim 6 including biasing means forexpanding said fluid-confining member to contain a fluid volume, saidpush button being depressible against said biasing means to decreasesaid fluid volume.

9. A control system according to claim 1 wherein said fluid-responsiveswitch comprises dissipating means for dissipating the pressureincreases due to at least one of said pulses after a selected timeinterval.

10. A control system according to claim 1 wherein said fluid pulses arepneumatic pulses.

11. A control system for producing an output signal to operate a devicecomprising a first fluid pulse generator generating a first fluid pulsein response to a manual force, a second fluid pulse generator generatinga second fluid pulse in response to another manual force, and afluid-responsive switch responsive only to substantially simultaneousreceipt of said first pulse and said second pulse to produce saidoutput,

wherein said fluid-responsive switch comprises a housing, a flexiblesealing member dividing said housing into first and second pressurechambers, a first pulse inlet port, a fluid outlet port, a vent port,all of said first pulse inlet port, said fluid outlet port, and saidvent port opening to said second pressure chamber, a second pulse inletport opening to said second pressure chamber, a control port betweensaid first pulse inlet port and said vent port, pressure dissipatingmeans from said second pressure chamber, and signal means connected tosaid fluid outlet port and responsive to an increase in pressure at saidoutlet port to produce said output signal, said sealing member being,when unflexed, spaced from-said control port to allow the increase inpressure in said first pressure chamber due to receipt of a fluid pulsefrom said first pulse inlet port to be relieved by said vent port, saidsealing member being flexed in response to an increase in pressure insaid second pressurechamber due to receipt of a fluid pulse from saidsecond pulse inlet port to close said control port, whereby the increasein pressure in said first pressure chamber produces a fluid output atsaid fluid outlet port, said pressure dissipating means dissipating theincrease in pressure in said second pressure chamber after a selectedtime interval to enable said sealing member to return to its unflexedposition.

12. A control system according to claim 11 wherein each said pulsegenerator comprises a manually depressible push button, and a controlmember, connected to said push button and movable over adistance whensaid push button is depressed to generate said fluid pulses.

13. A control system according to claim 12 including biasing meansbiasing said push button to a normally OFF position.

14. A control system according to claim 12 wherein said push buttons arespaced apart in a manner allowing an operator to push only one buttonwith each hand.

15. A control system according to claim 12 wherein said control membercomprises a piston movable over a distance to generate a pulse.

16. A control member according to claim 12 wherein said control memberis a'flexible diaphragm confining a fluid volume and having a fluidoutlet, said push button, when depressed, decreasing said fluid volumeto generate a fluid pulse. 7

17. A control system according to claim 11 where said dissipating meanscomprises a bleed valve for bleeding the increase in pressure in saidsecond pressure' chamber as soon as said second fluid pulse enters saidsecond pulse inlet port.

18. A control system according to claim 12 wherein said fluid pulses arepneumaticpulses.

1. A control system for producing an output signal to operate a devicecomprising, a first fluid pulse generator generating a first fluid pulseonly in response to a first manual force change, a second fluid pulsegenerator generating a second fluid pulse only in response to a secondmanual force change, fluid responsive switching means for providing anoutput signal when actuated to assume a first condition, first meanscoupled to said first and second pulse generators for requiring anoperator to substantially simultaneously effect said first and secondforce changes to produce said first and second fluid pulsessubstantially simultaneously to actuate said fluid responsive switchingmeans to assume said first condition, and second means for causing saidfluid responsive switch to always assume a second condition preventingthe occurrence of said output signal shortly after assuming said firstcondition.
 2. A control system according to claim 1 wherein said firstand second fluid pulse generators are spaced apart in a manner allowingan operator to apply only one said manual force with each hand.
 3. Acontrol system according to claim 1 wherein each said fluid pulsegenerator comprises a control member movable over a distance to generatesaid pulse.
 4. A control system according to claim 3 wheRein each saidfluid pulse generator comprises a manually depressible pushbuttonconnected to said control member.
 5. A control system according to claim1 wherein at least one of said fluid pulse generators comprises a fluidcylinder having an outlet, a piston movable in said cylinder to displacefluid through said outlet, a manually depressible push button connectedto said piston, and biasing means biasing said piston away from saidoutlet in the absence of manual force on said push button.
 6. A controlsystem according to claim 1 wherein at least one of said fluid pulsegenerators comprises a fluid chamber having a flexible fluid-confiningmember and having a fluid outlet, and a manually depressible push buttonconnected to said fluid-confining member, said button, when depressed,decreasing the fluid volume confined by said member to generate a fluidpulse at said outlet.
 7. A control system according to claim 6 whereinsaid flexible fluid-confining member is a flexible diaphragm.
 8. Acontrol system according to claim 6 including biasing means forexpanding said fluid-confining member to contain a fluid volume, saidpush button being depressible against said biasing means to decreasesaid fluid volume.
 9. A control system according to claim 1 wherein saidfluid-responsive switch comprises dissipating means for dissipating thepressure increases due to at least one of said pulses after a selectedtime interval.
 10. A control system according to claim 1 wherein saidfluid pulses are pneumatic pulses.
 11. A control system for producing anoutput signal to operate a device comprising a first fluid pulsegenerator generating a first fluid pulse in response to a manual force,a second fluid pulse generator generating a second fluid pulse inresponse to another manual force, and a fluid-responsive switchresponsive only to substantially simultaneous receipt of said firstpulse and said second pulse to produce said output, wherein saidfluid-responsive switch comprises a housing, a flexible sealing memberdividing said housing into first and second pressure chambers, a firstpulse inlet port, a fluid outlet port, a vent port, all of said firstpulse inlet port, said fluid outlet port, and said vent port opening tosaid second pressure chamber, a second pulse inlet port opening to saidsecond pressure chamber, a control port between said first pulse inletport and said vent port, pressure dissipating means from said secondpressure chamber, and signal means connected to said fluid outlet portand responsive to an increase in pressure at said outlet port to producesaid output signal, said sealing member being, when unflexed, spacedfrom said control port to allow the increase in pressure in said firstpressure chamber due to receipt of a fluid pulse from said first pulseinlet port to be relieved by said vent port, said sealing member beingflexed in response to an increase in pressure in said second pressurechamber due to receipt of a fluid pulse from said second pulse inletport to close said control port, whereby the increase in pressure insaid first pressure chamber produces a fluid output at said fluid outletport, said pressure dissipating means dissipating the increase inpressure in said second pressure chamber after a selected time intervalto enable said sealing member to return to its unflexed position.
 12. Acontrol system according to claim 11 wherein each said pulse generatorcomprises a manually depressible push button, and a control member,connected to said push button and movable over a distance when said pushbutton is depressed to generate said fluid pulses.
 13. A control systemaccording to claim 12 including biasing means biasing said push buttonto a normally OFF position.
 14. A control system according to claim 12wherein said push buttons are spaced apart in a manner allowing anoperator to push only one button with each hand.
 15. A control systemaccording to claim 12 wherein said control member comprises a pisTonmovable over a distance to generate a pulse.
 16. A control memberaccording to claim 12 wherein said control member is a flexiblediaphragm confining a fluid volume and having a fluid outlet, said pushbutton, when depressed, decreasing said fluid volume to generate a fluidpulse.
 17. A control system according to claim 11 where said dissipatingmeans comprises a bleed valve for bleeding the increase in pressure insaid second pressure chamber as soon as said second fluid pulse enterssaid second pulse inlet port.
 18. A control system according to claim 12wherein said fluid pulses are pneumatic pulses.